1. Field of the Invention
The invention relates to a light emitting diode package, particularly to a light emitting diode package which has different kinds of sealants.
2. Description of the Related Art
FIG. 1 shows a cross-sectional diagram illustrating a conventional multi-chip light emitting diode (LED) package 100. Referring to FIG. 1, several pyramid-like rib structures 104 in the shape of a pyramid are formed on a substrate 102 to divide the mounting surface S of the substrate 102 into multiple separate regions, each region being placed with a red LED chip 106A, a green LED chip 106B, or a blue LED chip 106C, and these LED chips are sealed on the substrate 102 by a same sealant 108.
Referring to the conventional design shown in FIG. 1, though the pyramid-like rib structures 104 may divide the mounting surface of the substrate 102 into multiple separate regions for spreading with different LED chips, they fail to divide the accommodation space of the substrate 102 into separate cavities for receiving different LED chips, and thus these LED chips are sealed on the substrate 102 by the same sealant 108 but not different kinds of sealants that is capable of being selected depending on the optical characteristic of each of the LED chips. For example, when all LED chips are sealed by the same sealant such as an epoxy resin, the short-wavelength emission of the blue LED chip 106C is liable to cause yellowing phenomenon in the epoxy resin and thus to reduce light emitting efficiency. Though a silicone sealant may be used for sealing all the LED chips to cure this problem, the silicone sealant is expensive to result in a considerable fabrication cost. Besides, since the pyramid-like rib structures 104 are not capable of providing sufficient height to confine the propagation paths of totally reflected light beams, the strong possibility that the emitting light of the LED chips are absorbed by the sealant 108 may further reduce the light emitting efficiency.